For instance, video telephones. A regular phone is bad enough. You're in the shower, say, and you hear the phone. It could be that important phone call you've been expecting. So you rush out of the shower, almost breaking your neck in the process, get your phone, and answer. You're flustered, you may have pulled a muscle that could turn out to be important to you someday, and you're trying to avoid electrocuting yourself with all the water you're dripping on that rather expensive electronic device. Are you really going to tell me that you would remember to turn off the picture on a video phone in such a circumstance? Video phones seem cool, but flashing a prospective employer is a bad idea.
Then there's flying cars. Yeah, because I really want to crash twice. Like nobody's ever going to run into another driver, or some innocent telecommunications tower (and wouldn't that make you popular). And then, after you're already bruised and possibly broken, you get to plummet to the ground, or through someone's roof (and wouldn't that, well, you get the idea). I frequently have to dodge drivers who obviously aren't looking where they're going when I'm not only on the crosswalk but crossing with the walk signal on. So you know there are going to be accidents up above. And, shortly thereafter, there will be accidents down below. Flying cars look cool, but applying the domino effect to an automobile crash is a bad idea.
Flying suits are similar to flying cars except that you have the added benefit of having nothing between you and the ground, not even the flimsy remains of a (formerly) flying car. But there's more. If you've ever seen a picture of someone flying with one of those, you'll recall the jets coming out of the end of the suit. In the general direction of the flyer's posterior. I don't know about you, but I don't think I want flaming hot gases aimed at any part of my body. And, as I get older, I find I do a lot more sitting, so that's a body part I especially don't want messed with. Don't get me wrong, flying suits definitely look cool. Until your bottom catches on fire. Then you don't look cool at all. You just look like a guy with his bottom on fire. And that's a bad idea.
Finally, we come to those transparent domes for living on airless planets. It looks cool. You're living on the Moon, and you can see the Earth rise as you're going to work, or sit in the park and see stars as we could never do here with all that silly air in the way. It would be spectacular, though I suppose it would be no big deal once you got used to it. But the point is, there have been a lot of stories about meteors and what kind of damage they could do to Earth. And we have an atmosphere that burns up the majority of those things before they can hit the ground. I don't think I want nothing between me and a huge chunk of metal, ice, and rock but a transparent dome. You're not just living in a glass house, you're living in a glass city. And the cosmos is throwing stones. And that's a bad idea.
Now, I don't want you to be put off innovation. We need inventive types to make the world a better place, or at least to make it more interesting. And we need people who are excited by new ideas, to invest in them and to buy them when they come on the market. Just don't set your bottom on fire.